Motor graders are often used for construction, road-building, rural road resurfacing, shallow ditching, field preparation, and other industrial activities requiring the preparation of a flat earthen or particulate surface. A motor grader typically includes a ground engaging element such as a plurality of wheels that convey the machine over the ground, and a large blade extending from the underside of the machine and disposed generally transverse to both the underlying surface and the direction of travel. The blade can generally be manipulated in a plurality of directions and dimensions by the machine operator.
As the machine traverses over the ground, the blade removes and displaces surface material that comes into contacting engagement with the blade. The vertical amount of material removed in a pass is referred to as the cut depth. Typically, the cut depth is operator controlled depending upon a subjective analysis of the operating conditions as well as the final desired grade level. It will be appreciated that, for larger cut depths, the impedance to the blade, and hence to the movement of the machine itself, can become rather large. In extreme cases, the machine wheels may begin to slip, causing the motor grader to mar or otherwise cause unevenness in the surface being treated. This can result is a substantial loss of productivity as the surface must now be repaired in many cases. Alternatively, to avoid the likelihood of wheel slip, the operator may take multiple passes of overly shallow cut depths. This also results in a substantial loss of productivity.
Current electronic blade control systems such as GPS-guided grading systems provide very precise elevation determination by precisely tracking the location of the blade edge. However, such systems do not prevent the machine from spinning out, i.e., spinning one or more wheels against the underlying surface, if the operator attempts too deep of a cut in a single pass. Although an operator may prevent spinouts by taking many light passes, removing only a small amount of material each time, this technique is also damaging to productivity. In particular, this technique requires substantially more time and fuel than would be needed if the machine were operated closer to its traction limit.
It will be appreciated that this background description has been created by the inventors to aid the reader, and represents concepts known to the inventors. It is not a discussion of, nor reference to, prior art, nor is this section intended to imply that any of the indicated problems were themselves appreciated in the art. While the principles described herein can, in some regards and embodiments, avoid the problems described, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of the claimed invention to solve any specific problem noted herein.